Locomotive boiler



June 28, 1927. 1553359.93

H. MccABE LocoMoTIVE BOILER Filed Aug. 17, 1926 Patented June 28, 19.27.

UNITED STATES HUGH MCCABE, 0F LAWRENCE, MASSACHUSETTS, ASSIGNOR TOMCCABE MANUFAC- TURING COMPANY, 0F LAWRENCE,

MASSACHUSETTS, A PARTNERSHIP.

LOCOMOTIVE BOILER.

Application led August 17, 1926. Serial No. 129,760.

rThe present invention relates to an improvemcnt in locomotive boilers.

The fire box of locomotive. boilers is subject to wide fluctuations oftemperature due to the variations in fire necessarily incident to makingsteam under the varying conditions demanded by service, and owing tobanking of the fires which lowers the temperature still more. As aresult of these fluctuations in temperature the fire box is subject-edto serious variations of stresses. The fire box is well braced to standthe pres sure of the steam, but when the temperature falls the metalcontracts, and when it rises the metal expands, and the changes ofdimensions incident to this cause sever-e stresses to be exerted uponthe portins of the re box subjected to the greatest variation intemperature, and particularly to the corners. It is the practice ltofillet the sides of the fire boxes to avoid sharp corners, but in thecase of a tube sheet this is obviously a matter of such difficulty thatit has not been attempted. The tube sheet is .ordinarily provided with aflange at its edge to which the sides of the fire box are riveted andthe corner between the tube sheet and its flange is subjected to theseverest stresses, and ordinarily the tube sheet requires replacementfrom time to time.

rThe lap joint Where the sides of the fire box lap over the flange ofthe tube sheet pre sents a thickness of metal about double the thicknessof the lire box plates, and according to the present invention it isproposed to thicken the tube sheet at the flange corner so as thereby tostrengthen it at the place where it commonly gives out first. The objectof the invention is to improve the locomotive boiler by producing` amore durable tube sheet, and to this end the invention consists in thetube sheet for locomotive boilers .hereinafter described andparticularly defined in the claim.

In the accompanying drawings illustrat ing the preferred form of theinvention, Fig. l is a longitudinal section of a boiler illustrating thefire box provided with the tube sheet of the present invention; Fig. 2rep-' resents the joint between the side plates and tube sheet of thefire box on an enlarged scale, taken on the line 2 2, Fig. 8; and Fig. 3is a front elevation of the tube sheet, the tube holes being omitted.

The illustrated embodiment of the invention is described as follows: Theboiler 1 is provided with a fire box 2 supported in place therein in theusualv manner. The tire box comprises the side sheets 3 'and the tubesheet 4. The tube sheet consists of a plate of metal of the thicknessdesired for the fire box, having a thicker portion 5 at the anglebetween the plate and the flange 6. vThe tube sheet is made of metal ofthe thickness of the corners 5, and flanged by any usual or convenientmethod, preferably cold flanged, as this method of Hanging securesgreatest strength of metal. After the sheet is formed the portion 7,indicated within the dotted lines, is milled out, and the portion 8 ofthe sheet is also .milled out, leaving the flange 6 and sheet A1 of thedesired thickness. lt will be observed that when the side sheets 3 ofthe fire box are riveted to the flange 6 of the tube sheet, the metal ofthe double layer will have a thickness approximately equal to thethickness of the corner of the flange, so that the portion of the firebox extending from the. inner end of the box around to the corner of thetube sheet to the tube sheet itself will be of substantially uni- Y formthickness.

Vhen the fire box is heated to the high temperature incident to use, thejoint between the inner edges of the side sheets and the flange of thetube sheet, and the corner of the tube sheet being of substantially thesame thickness, will equalize and distribute the strains throughout thislarge mass of metal, and thereby tend to secure a more equabledistribution of stresses. So also when the fire box cools again, thestresses will be distributed throughout this cold mass of metal, andwill not be localized at the corner between the tube sheet and itsflange as heretofore, with the result that the tube sheet will have muchlonger life than the tube sheet heretofore employed.

Having thus described the invention, What isl claimed is:

A tube sheet for fire boxes of locomotives having a tube sheet properformed with a flange at its edges, the angle between the tube sheet andthe flange being thicker than the tube sheet properto enable it to bearthe stresses of expansion and contraction due to fluctuations in thetemperature.

In testimony whereof I have signed my name to this specification.

HUGH MCCABE.

